CrazyTechThoughts

REST stands for Representational State Transfer. Roy Fielding, the father of HTTP protocol, had coined the term in his doctoral thesis. REST is not a software, rather it is a concept or an architecture. The biggest use of REST architecture is in WWW (World Wide Web). The services that conforms to REST standard are termed as RESTful services. REST based services contain a client and a server. The server contains resources that can be represented by various states. A client initiates the request to server when it is ready to transition it's state. The server responds with the required state. The REST based web service is quite popular now. This type of web service is called RESTful web service. In RESTful web service we represent a service by an URI. Common HTTP methods are used to request for a specific state transfer. Create PUT Update POST Read GET Remove DELETE I have used an open source java library called Jersey  for creating this simple RESTful web service. ...

Web service is a popular medium of communication between devices over a network. But most of the time you find yourself behind a http proxy server to connect to the network. Proxy servers are often found in company networks. The main reasons for their introduction are - security, resource caching, auditing etc. But ultimately they block unauthorized access to internet from the inside network. This leads to the problem we are going to solve now. We are going to use w3schools temperature converter service ( WSDL download ) for testing. Make sure you are actually running this code behind a http proxy server. You also need to know the proxy server's host name and the port no.  I'll assume that you can generate the client stubs using JAX-WS (or some other tool). I have used wsconsume tool to generated my stubs. In my case,  com.w3schools.TempConvert is the implementation class and  com.w3schools.TempConvertSoap is the interface. Then I have a com.w3schools.client.WSClie...

Today I'll try to explain how easily one can build a JAX-WS web service. Web Services are very popular now-a-days. They are used every where. But I found it difficult to write my first web service with jax-ws, partly because I was trying myself and partly because I could not get a simple explanation of steps. That is why I'll try to show the simplest web service possible using jaxws. First thing first, what do you need to build your first jax-ws web service. JDK 1.6 (I used update 23) Eclipse IDE (you can use some other IDE as well) Are you kidding? nothing else. JAX-WS 2.0 is actually Sun's (now Oracle) reference implementation of Web Service stack. It is bundled with JDK 6 and above. First you need to create a Java project in Eclipse. Then create a class called com.ws.HelloService . This will be our web service class. Have a public method in this class which will be exposed as web service. Below is the code - The catch here is the @WebService annotation. Thi...

My latest project involves JQuery for UI development. Frankly speaking, I did not have much idea of JQuery before. But I found it very easy to understand. All APIs are well documented with lots of examples available on Internet. The best feature of JQuery is its plugins. There are thousands of plugins available to play with. For every need of my web app I could find a plugin. In my web app I am using JQuery Form plugin to submit the forms through AJAX. The return from my servlet is JSON object. The form plugin works great for all my forms. Well almost all, there is a HTML form which has a file upload box along with other input fields. This form was not able to get the response in JSON format. Though it worked in Google Chrome, but Firefox was presenting me with a file save dialog box. I did a lot of googling to find out whats going on. Finally I observed that the problem is with HTTP headers that the form submit request has. Here are the headers captured by Chrome Request heade...

I could not post anything last month though all the time I was dying to post something. The reason behind this was I change in my profession profile. Actually, I changed my employer. All of the last month I was busy in official work and to settle down in my new office. The last week of the year is normally a holiday in the new company. So, I could rest a while in my home and able to write the blog post. Though I had a couple of other topics in mind but writing them will take more time which I don't want to spend during the festivities. So, I'll discuss about a simple but useful thing. How many of us in Java sphere use log4j for logging? You know the answer. log4j is a very popular logging framework. Configuring log4j is quite simple. Still when you get the task of doing it, you try to find an example (I do the same). That is why I'll show a simple log4j configuration to print to a file. There are 2 ways to configure log4j, log4j.properties and log4j.xml. I prefer the...

JDK 7 is the next release of Java language. There are lot of expectations from this release. For the first time Java is being modeled outside Sun Microsystems. Now JDK 7 has got a net host, openJdk community. There are quite a few features planned in JDK 7. Some of them may prove to be a milestone for Java language. But my personal liking is a very small feature rather project called Project Coin . Coin serves to add small language features to Java which will make programmer's life easy. The JavaOne 2010 presentation for Project Coin lists the following features as accepted ones in JDK 7 time frame. Binary literals and underscores in literals Strings in switch Varargs warnings Diamond Multi-catch and more precise rethrow try-with-resources (formerly known as Automatic Resource Management, ARM) Out of these features, the most attractive to me was "Strings in switch". This is something I've longed for from my college days. I mean, though it was not Java (it...

Few days back I was disturbed with some maven build issues in office. I got back home pretty late. Already, as you can understand, mood was off. I thought of relaxing by watching a good movie but next day I had an interview scheduled. So, I had to brush up my skills a bit (I don't use them often in office :-) ). The first topic I started with was Singleton pattern. This one is so famous among interviewers that you better be able to explain it. I had read the pattern many a times already. Nothing to prove the book wrong, never occurred to me. But that day, may be due the horrible mood, I challenged the pattern. I thought I'll find ways to break the pattern down. I wanted to create 2 Singleton instances in same JVM. Thats how the attack began. Below is the code for creating a Singleton class Here is the code to test the pattern I have used VisualVM (comes as part of JDK 6) tool to check the no. of instances for Singleton class. You just need to pass a VM argu...